Cold Acclimation Green Crab Experiment Part 11

Experiment log: Acclimation week

Important spreadsheets:

Came back from a week away! Catlin and Heidi did an amazing job taking care of the crabs and keeping notes in the binder
Noticed that the rack lights were not on when I walked in. I gave them a little tap and they sprang back
Crab 33 in Tank 2 dead

Figures 1-2. Room without rack lights on

T5-T7 filters and air stones were off, so several crabs were clinging onto the mesh at the top of the tank. I must not have turned them back on after cleaning
T7 had eggs in the tank, likely from crab 118
Ammonia check
Replaced 60% of water
Added ammonia conditioner to all tanks
Fed crabs
No mortalities!
Catlin and Heidi rearranged the experimental tanks so they were all on the same level under a rack light. They also moved cords to racks away from the tanks and covered the extension cords with trash bags so they wouldn’t get wet.

T1-T3 air stones and filters were off. Catlin and Heidi must have forgotten to turn them back on after rearranging the cords
Took HOBO data for tank temperatures
- A couple of loggers were accidentally set to 10 second logging, so they were completely full. I relaunched these loggers today
- I noticed that T5-7 were averaging ~ 17ºC, with big swings between 16ºC and ~18.5ºC during the day. T1-3, however, stayed constant at 16ºC. First, this is a good sign that my cold tanks are in the right place! I also expect the temperature fluctuations to not be an issue once the room is colder and heaters are in. However, I did lower the temperature of the room to 13.5ºC to try and get tank averages closer to 14 or 15ºC. I’ll check HOBOs again on Thursday and if needed, lower the temperature further.
Figures 1-2. Example HOBO logger profiles for tanks.
Cleaned tanks
Fed crabs
- Brought in my 1/4 tsp for feeding!
Updated all online spreadsheets
Discarded tubes for dead crabs
Labelled all remaining crabs!
- Catlin and Heidi caught several carbs in the traps over the past week that we distributed between tanks. We added at least a few females and males to each tank

Cleaned and fed tanks
120, 122, and 127 dead. These are all crabs from Eel Pond! They didn’t seem to be in too bad of a state so I’m not really sure what happened with them

Cleaned and fed tanks
14 in T1 looked like it was about to molt! Instead of letting it molt in the tank and get eaten (leaving me to clean up yucky crab bits) I moved it to empty T4 to molt. Maybe once its shell hardens up again I can relabel and move it back?
Made TTR spreadsheet and picked crabs to dissect for the 0 hr time point

Water change, ammonia check, filters changed
124 died (and was disgustingly actively being eaten). I raelly don’t know why T7 is such a high mortality tank :/
13 died (but thankfully was not being actively consumed)
Fed crabs

Written on June 16, 2024